A pyrotechnic composition is generally prepared by adding a fuel to an oxidizing agent. The fuel reacts with oxygen derived from the oxidizing agent to produce an oxidized product together with heat. Taking advantage of this heat, many effects such as color, motion, light, smoke, noise and the like can be created.
The pyrotechnic composition is typically employed as firework composition wherein a flame reaction plays the role. For example, to make a red color, a strontium salt is used as a color producing agent. Although strontium nitrate had been used, strontium carbonate is mainly used at present since it is very stable and gives a beautiful color. Similarly, to make a green color, barium nitrate is typically used. To make a yellow color, sodium oxalate and calcium carbonate are typically used. To create a blue color, pairs green and copper oxide are typically used. To make a purple color, a mixture of strontium carbonate and copper oxide is typically used. To make a white color, aluminum is typically used.
Japanese launching fireworks are generally “Chrysanthemum type round shells” blooming in circle. In the round shell, “stars” are arranged inside around a package such that the stars burn all together and also go out all together. As the star, a spherical star called as “a multi-coated star” is used. The spherical star is prepared by directly putting in a rolling caldron such as a concrete mixer a round cereal such as a foxtail millet seed and a rape seed or shot which is used as a core, adding a mixture comprising an oxidizing agent, a fuel, a color producing agent and a paste together with water while rotating the rolling caldron to grow a star until a layer resulting from the mixture having a suitable thickness is adhered to the core, and spreading over a drying table to be dried. After drying well, the star is charged in the rolling caldron again to further grow. This work is repeated until the star having a desired size is obtained. For example, in order to obtain a star of 20.5 mm in diameter used for a 10-gou (=30 cm) aerial shell, the above work is repeated about 35 times and it takes at least about-17 days to finish.
In a fireworks display, exhibition fireworks are indispensable. The exhibition firework includes lances and quick matches. “Lance” comprises a paper pipe in which a mixture of an oxidizing agent, a color producing agent and a fuel is filled, such as a “susuki (eulalia)” and a “torch” of toy fireworks. In order to make six colors, i.e. red, green, yellow, blue, purple and white (silver) colors, suitable color producing agents are used.
Operations for the manufacture of stars and lances are laborious. Especially in the manufacture of stars, it takes a considerable time to finish as described above, which lowers the productivity. In the manufacture of lances, the operation of uniformly filling a powder in a paper pipe is laborious.